3.3 Redundancy analysis
The RDA plot showed that the first two axes jointly accounted for 93.9
% of the variance (Fig.4). The results showed that CAT activity of
submerged plants in each group was negatively correlated with other
physiological indexes. Root vitality was positively correlated with
biomass, plant height, and root length. SOD activity was positively
correlated with Chl-a, Chl-b, Chl-a+Chl-b, and MDA contents. The great
distance among the substrate groups indicated that different substrates
had different effects on the plants.